Three automatic and smart view planning approaches for 3D digitization of unknown objects [Trois approches de planification de vue automatiques et intelligentes pour la numérisation 3D d’objets inconnus]
Khalfaoui S.,IUT |
Seulin R.,Laboratoire dElectronique |
Fougerolle Y.,Laboratoire dElectronique |
Fofi D.,Laboratoire dElectronique
Traitement du Signal | Year: 2014
This paper presents three methods for the digitization of 3D objects without prior knowledge on their shape. The first method is simple and naïve and is based on the generation of view points by sampling the bounding box of the acquired data at each step of the acquisition process. The second method is an analysis of the orientation of the scanned parts. The third method explores the barely visible surfaces and is a combination of the angular visibility and the real one by ray tracing. Tests with objects of different complexity classes were performed. The results of digitization are provided and prove the efficiency and the robustness of our approaches. © 2014 Lovoisier.
Karamian E.,Isfahan University of Technology |
Monshi A.,Isfahan University of Technology |
Bataille A.,CNRS Materials and Transformations Unit of UMET |
Journal of the European Ceramic Society | Year: 2011
SiC whisker is excellent in characteristics such as specific strength and chemical stability, and is useful as a composite reinforcing material. In this paper, the effect of the formation of in situ nano SiC whiskers on strength and density of bauxite-carbon composites was studied. Samples were prepared composed of 65. wt.% bauxite, 15. wt.% SiC-containing material, 10. wt.% coke, 10. wt.% resole and different values of silicon additives. The pressed samples were cured at 200°C (2. h) and fired at 1100°C and 1400°C (2. h). XRD, SEM, TEM, EDX, FTIR and STA were used to characterize the samples. These characterizations indicated that SiC nano whiskers, 50-90. nm, are single crystalline β-SiC with mechanism of the formation VLS. So, firing temperature is an important factor. As, SiC nano whisker was formed at 1400°C and improved CCS values up to four times in sample containing 6. wt.% ferrosilicon. © 2011 Elsevier Ltd.
Azam F.,Bangladesh University of Engineering and Technology |
Islam M.S.,Bangladesh University of Engineering and Technology |
International Journal of GEOMATE | Year: 2016
In this research, the prospect of tunneling by cut and cover and New Austrian Tunneling Method (NATM) for underground metro rail system in Dhaka city was evaluated. Both conventional analysis and 2D finite element analysis using an elasto-plastic constitutive model named as subloading tij considering plane strain drained condition were performed. A comparison was made between results obtained from conventional analysis and numerical analysis for braced cuts. The behavior of different types of soil layers are simulated. Effects of different loading conditions and presence of water table have been considered for both cut and cover and NATM excavation method. Comparing the results of different foundation types, it has been found that for shallow foundation the surface settlement at the position of the foundation is larger than that for pile foundation. From analyses, it was revealed that for greenfield like Tongi to Uttara along the MRT-4, cut and cover is more appropriate considering its simplicity in execution and NATM is preferable at flyover junction points in Cantonment and structurally obstructed places. © 2015, Int. J. of GEOMATE. All rights reserved.
Gong X.J.,CNRS Research Department of Automotive Engineering |
Hurez A.,IUT |
Verchery G.,CNRS Research Department of Automotive Engineering
Polymer Testing | Year: 2010
This work covers the problems encountered in correctly determining mode I interlaminar fracture toughness of composite materials. Pure mode I tests were performed on double cantilever beam (DCB) specimens composed by quasi-homogeneous and uncoupled multidirectional (MD) laminates using 16 or 26-ply: [α/-α2/α/-α/α2/- α]sym or anti-sym and [0/α/-α/02/- α/0/α/02/α/-α/0]sym, with α = 0°,15°,30°,45°,90°. A finite element analysis shows that the non-uniformity ratio β=(GImax-GIav.)/G Iav% depends not only on the parameter Dc = D 12 2/(D11D22), but also on the specimen geometrical ratios a/b and a/h. The condition of Dc<0.25 is not sufficient to assure a uniform GI width-wise distribution. If we want to study the crack growth between any ply angles, it is difficult to find lay-ups having β<10%. In fact, the crack initiation in MD DCB specimens usually occurred at the middle of the specimens, where GI attained a maximum. Hence, the critical energy release rate GIC has to be measured by the maximum instead of the mean of GI. © 2010 Elsevier B.V. All rights reserved.
Tehrani A.F.,Southern Methodist University |
Harooni M.,IUT |
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2012
This paper deals with the investigation of wear behavior of TiNi and TiNi-TiC clads applied to plain carbon steel by tungsten inert gas (TIG) surfacing process. In this regard, ball milled Ti-Ni and Ti-Ni-C powder mixtures were used as feedstock materials. The clad layers were investigated using X-ray diffractometery (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness measurements and reciprocating wear tests. The results of microhardness measurements indicated that hardness values of TiNi-TiC composites were higher than those of TiNi by approximately 100HV. It was also shown that the wear behavior of TiNi-TiC clads was better than that of TiNi. Further investigations indicated that the dominant wear mechanisms in TiNi and TiNi-TiC clad layers were delamination and surface fatigue, respectively. Copyright © 2012 by ASME.